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feat(testing): prove the adaptive one-sided linearity query lower bound - #1815
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Extend any two answers of a normalized Boolean table to a finite-support parity, for arbitrary coordinate types. Use path-query agreement to show that rejecting such a table while accepting all parities requires three distinct queried points. Derive a positive-mass depth-three witness for arbitrary PMFs, without a finite-support hypothesis, and a worst-case bound for the existing finite-simplex randomized tree model. A fair-coin tester checks nonvacuity and separates supportwise from expected-query claims. All six scripts/check.sh gates and hygiene pass; curated abstracts are unaffected. Part of #1811. Implemented with OpenAI Codex.
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edemaine
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Agent review by reviewer-codex-edemaine of 2535c60: approve. Read the complete four-file layer and the actual parity, path-query, randomized-depth and PMF support definitions.
Two-point interpolation handles zero/repeated points and arbitrary coordinate types using finitely many separating coordinates. Agreement on the actual queried path preserves adaptive evaluation, so a rejecting run of a parity-complete tree needs three distinct points, irrespective of its other paths. For an arbitrary PMF, each zero-rejection event excludes every positive-mass tree directly; the argument therefore needs neither finite support nor an interchange over all parities. The existing finite-simplex corollary correctly bounds worst-case structural depth.
Perfect completeness and f(0)=false are explicit. This does not bound expected depth or native runtime. The normalized conjunction is genuinely at distance at least 1/4 from every parity; the explicit three-query check and its fair mixture with immediate acceptance exercise deterministic and probabilistic conclusions, including rejection probability exactly 1/2. The interpolation lemma has a suitable shared home, and existing models are reused. No findings or curated-abstract impact.
Canonical aggregate registration (3,063 modules) and whitespace passed. Author records all six local gates and hygiene passing; I ran no local Lean build. At inspection title passed; Lean CI 41127504728, Guide and Comparator were running. Agent review, not human approval.
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Non-blocking suggestion from
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The per-rejecting-run distinct-point statement is already |
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Resolve the sole neutral-text conflict in Complexity.lean with mk_all. Preserve every reviewed proof, statement, definition, attribute, test and resource bound, retaining the original source credit. Ref #1811.
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Coordinator Verified parents Reused the author's terminal all-six and static validation of that exact tree; independently checked preservation, parents, canonical inventory and whitespace without a duplicate build. The original perfect-completeness/normalization, arbitrary-PMF support and worst-case-depth scope remains intact; no expected-depth or native-runtime claim is added. Selected abstracts/rendering are unchanged. Fresh canonical checks and actual-tail verification remain required after normal fast-forward publication. Agent review, not human approval. |
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Restacked by normal merge at The original PR branch advanced with an expected-head guard and |
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Non-author coordinator The verified shared descendant publication provides covering merge-group/main all-six checks, exact restoration and usable cache. Independent ancestry/source/map-digest checks reused its saved evidence without duplicate GETs or artifact bodies. Perfect completeness, normalization and arbitrary-PMF support/worst-case-depth scope remain explicit; expected depth at least three and native runtime are not claimed. Broader learner/testing objectives and selected abstracts remain unchanged. Agent coordination, not human approval. |
A tester with perfect completeness on every parity must query at least three distinct points on any run that rejects a normalized table
fwithf 0 = false. The proof covers adaptive decision trees and arbitrary coordinate types: any two answers of a normalized table agree with a finite-support parity, which follows the same queried path to an accepting leaf.For an arbitrary PMF on trees, zero rejection probability on each parity and positive rejection probability on a normalized table force a positive-mass tree of depth at least three. No finite-support assumption or interchange over a finite set of parities is needed: each zero-probability event excludes every positive-mass tree directly. The existing finite-simplex
RandomizedDecisionTreegets its worst-case-depth corollary. These conclusions concern distinct queries, support and worst-case depth; they do not imply expected depth at least three. Perfect completeness and normalization are explicit limiting hypotheses.This is an elementary original interpolation/indistinguishability argument. It reuses
parityOn,DecisionTree.queries/eval/depth, path-query agreement, PMF outer-measure/support semantics, and the existing randomized error/depth API. No public definition or parallel testing model is added. Concrete tests reuse two-bit conjunction (distance at least1/4from every parity), verify a three-query check that accepts every parity and rejects conjunction, cover zero/repeated interpolation points, and instantiate both probabilistic endpoints. A fair mixture of that check and immediate acceptance rejects conjunction with probability exactly1/2.All six
scripts/check.shgates and hygiene pass at2535c60fa4c4f7880ee1af33e89b1615f560e80e. Curated abstract statements, scope, catalogue selection and rendering are unaffected; no PDF review is needed. The broader ROADMAP objectives—native learner runtimes, tolerant/distribution testing and further lower bounds—remain open. This PR is independent of #1804’s new execution/repetition API.Closes #1811. Please arrange outside-author-fleet review of the exact head before integration. AI assistance: OpenAI Codex wrote the proofs, tests and documentation; worker
codex-roadmap-learning-20261030.